Tomatoes are the most popular vegetable grown in the United States. While they are easy to grow, sometimes they are a little temperamental. They like warm weather in the spring when they are set out. If the spring is cold and the ground remains cold, their roots become chilled, and it takes a long time for them to recover. Putting black plastic around the tomato plants can warm the soil temperature by 10 degrees. As they grow they like steady warm temperatures and even moisture. If the temperature changes suddenly and reaches above 90 degrees when they are blooming, they may drop their blossoms. Likewise if it goes below 55 degrees, they may drop their blossoms. If they become too dry they may also drop their blossoms. In time they will bloom again. The following are some conditions we often see with tomatoes.
- Blossom-end rot: This is when large black spots form on the blossom end (the bottom) of the tomato. It is caused by poor calcium uptake due to inconsistent moisture, or uneven moisture to the plant. If this occurs remove and tomatoes with this condition and provide consistent moisture. Tomatoes should have one inch of water per week. If there is a dry spell, water deeply (not often) and to the base of the plant.
- Cat-facing tomatoes: These are tomatoes which have irregular shapes and lines, especially at the top of the tomato. It is caused by temperature shifts and incomplete pollination in cold weather at flowering time. There is nothing you can do about cat-facing, other than select a variety that is resistant to this condition. This does not effect the flavor, the tomato will still taste good.
- Green shoulders: These are green or yellowish areas on the top of the tomato where it is connected to the stem. The tomato will appear ripe except of these area which can be spots or the whole top area. It is caused by hot temperatures when the fruit is forming or lack of foliage to protect the top of the tomato from the hot sun. To protect itself the tomato tissue and skin become tough and it will not ripen properly. There is nothing that can be done to change this if it occurs.
- Sun scald: This can happen anytime there is a spike in the temperature above 90 degrees. If the fruit is far from ripe, the entire fruit can possibly rot. Just remove damaged tomatoes.
- Split skin or cracking: This condition happens when the plants experience accelerated growth, which is brought on by a sudden increase in moisture after being dry. Usually brought by summer rain after dry periods. If consistent moisture is provided this usually will not happen. If tomatoes are overripe they may also crack or split. Cherry tomatoes will crack with the slightest shift in weather. To prevent this try to keep all ripe fruit picked, especially before rains.
- Thick, tough skin tomatoes: Many of the hybrids have tougher skins bred into them for shipping purposes. Varieties like Roma and Plum tomatoes are genetically bred examples of this. Tough skin is also produced on tomatoes when the temperature is hot and dry during the summer. Even if they are watered evenly and consistently, when the sun is hot and the air temperature is hotter during the day, the tomato will develop a thicker skin to help conserve its moisture. Again there is little that anyone can do. Mulching around the plant will help conserve moisture, but there is no control of hot air temperature.
Tomato plants are really vines, and as they grow they can become very large and heavy. One way to ensure that most of the fruit will ripen, is to pinch or cut back the plant so there are only three or four main shoots that are allowed to bear fruit. Simply pinch out sucker (the leafy shoots that grow in the leaf axil or "V" between the central trunk (stem) and lateral branches) in early summer as they grow, or cut out small branches this time of summer, so that only the main three or four branches are allowed to bear fruit. There will be a few less tomatoes, however they will be larger, and more of them will ripen. The plant will then be lighter and more manageable, and not a massive, heavy, tangled vine.
Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.
